This invention relates to a non-hydroquinone developer composition and its method of usage in development of photographic elements. More specifically, this invention relates to a non-hydroquinone developer composition which is particularly useful in the development of various types of photographic black-and-white photographic elements to assuredly achieve a lith quality development without the need for the presence of toxic hydroquinone. Even more particularly, the photographic developing composition of the present invention is advantageously used to develop internally boosted silver halide emulsions containing a hydrazine compound functioning as a nucleating agent.
High contrast development of black-and-white lithographicfilms has been accomplished for a number of years using special developers which are referred to in the field as xe2x80x9clithxe2x80x9d developers. As explained in U.S. Pat. No. 4,988,604, in conventional xe2x80x9clithxe2x80x9d developers, high contrast is achieved using the xe2x80x9clith effectxe2x80x9d, also referred to as infectious development, as described by J.A.Z. Yule in the Journal of the Franklin Institute, vol. 239, 221-230, (145). The traditional xe2x80x9clith developersxe2x80x9d are characterized by the presence of hydroquinone as the sole developer and a low sulfite ion concentration so as not to impede the infectious development mechanism. However, the conventional xe2x80x9clithxe2x80x9d developers suffer from a number of recognized serious deficiencies which encumber their utility. For instance, the developer exhibits low capacity as a result of the fact that it contains hydroquinone as the sole developing agent and, further, aldehyde tends to react with the hydroquinone developer to cause undesirable changes in development activity. Further, the low sulfite ion concentration is inadequate to provide effective protection against aerial oxidation. As a consequence, the conventional xe2x80x9clithxe2x80x9d developer solution is lacking in stability.
One known alternative to the use of conventional xe2x80x9clithxe2x80x9d developers is disclosed in U.S. Pat. No. 4,269,929. This patent describes high contrast development of photographic elements as performed in the presence of a hydrazine compound with an aqueous alkaline developing solution, which has a pH of about 10 and below 12 and contains a dihydroxybenzene developing agent, a 3-pyrazolidone developing agent, a sulfite preservative, and a contrast-promoting amount of an amino compound as a xe2x80x9cboosterxe2x80x9d.
While such an amino xe2x80x9cboosterxe2x80x9d containing developing composition yielded improvements in capacity, stability, and contrast, among other things, the inherent disadvantages of incorporating amino compounds as xe2x80x9cboostersxe2x80x9d in developing compositions soon became recognized in the prior art, such as toxicity, excessive volatility, lack of solubility, cost, and so forth, as explained in U.S. Pat. No. 4,988,604.
Accordingly, another proposal has emerged in the field which involves incorporating the amino (booster) compound into the silver halide photographic element itself, so that the amino compound is utilized as a so-called xe2x80x9cincorporated boosterxe2x80x9d, such as described in U.S. Pat. No. 4,914,003. In such xe2x80x9cincorporated boosterxe2x80x9d systems, the amino compounds which function as xe2x80x9cboostersxe2x80x9d and also hydrazine compounds which function as xe2x80x9cnucleatorsxe2x80x9d are incorporated into a silver halide emulsion, or other hydrophilic colloidal layers, in the silver halide photographic element to provide a so-called xe2x80x9cinternally boostedxe2x80x9d emulsion or one containing a hydrazine compound. For example, in this regard, representative literature includes U.S. Pat. Nos. 4,988,604, 4,975,354 and 4,994,365 and World Patents WO 92/15042 and WO 93/02389.
Also, a more recent discussion and overview of internally boosted emulsion technology is described by a publication by D.L. Kerr, entitled xe2x80x9cAN ENVIRONMENTALLY IMPROVED NUCLEATION PROCESS FOR GRAPHIC ARTS IMAGINGxe2x80x9d, ISandT""s 46th Ann. Conf. (1993), pp. 268-270.
However, these prior art systems still relied, at least preferably, on the use of hydroquinone-based developing agents and as preferably used in a pH range of about 9 to about 10.8, such as explained in U.S. Pat. No. 4,988,604.
However, serious disadvantages from an ecological and toxicological standpoint are associated with the use of such hydroquinone-based developing systems. For example, hydroquinone has allergenic effects. Therefore, the use of hydroquinone poses certain handling and disposal problems in view of applicable health, safety and environment guidelines and regulations.
WO 93/11456 describes a rapid access developer for hydrazine-containing films comprising at least one alkanolamine in an amount of 5-50 g/l; at least one ascorbic acid developing agent; and having a pH in the range of 10.7 to about 12.0. The developer may further contain KOH and potassium carbonate. However, as discussed below, many alkanolamines possess the undesirable characteristic of toxicity, excessive volatility and unpleasant odor. Furthermore, alkanolamines tend to adversely affect high contrast lith image performance.
EP 603586 discloses a concentrated developer containing an ascorbic acid type compound, a 3-pyrazolidone auxiliary developing agent and at least one basic compound selected from an alkali metal carbonate, sulfite or hydroxide. The combined use of a carbonate and sulfite is preferred. The pH of a working strength developer is within the range of 9.0 to 11.0.
U.S. Pat. No. 5,196,298, which corresponds to European Patent Application No. 0 498 968 published Aug. 19, 1992, proposes a photographic developing solution for immersion development having a pH of at least 12.0 and containing more than 0.4 mols/liter of a sugar derivative, or an alkali metal salt thereof, such as l-ascorbic acid and iso-ascorbic acid, which preferably contains no other developing agents and no sulfite ions. The developer solution of U.S. Pat. No. 5,1 96,298 is described as permitting the development of graphic arts photographic materials with lith quality while permitting the disposal of the depleted developer solutions in a more environmentally ready manner.
U.S. Pat. No. 5,098,819 also discloses a non-hydroquinone and non-alkali metal hydroxide containing photographic developer composition. The non-hydroquinone developer solution of this patent contains a developer selected from ascorbic acid and sugar-type derivatives thereof, together with a sulfite, an alkali metal carbonate and a 3-pyrazolidone developer compound, wherein the developer solution has a pH range of 9.75 to 10.6. The U.S. Pat. No. 5,098,819 describes the developer composition as being subject to degradation at pH""s in excess of about 10.6. Likewise, Japanese Published Patent Application No. 59-191035 published Oct. 30, 1984, discloses a developer composition, which is especially adapted for processing a silver halide emulsion containing a black dye, wherein the developer is described as containing ascorbic acid, alkali metal carbonate, alkali metal sulfite and alkali hydroxide in a pH range of 10 to 14. However, these two latter-mentioned publications do not describe lith developers in particular, nor do these publications describe testing data which shows lith quality development.
However, in these patent specifications, there is no disclosure or suggestion that these developers can be used as developers for a silver halide photographic material containing a hydrazine compound as a nucleator to obtain a high contrast image.
In actuality, these above-mentioned non-hydroquinone photographic developer solutions do not permit the attainment of lith quality.
Therefore, the art has urgently awaited the discovery of a developer composition which does not require a hydroquinone developing agent, minimizes the need for other toxic chemicals such as alkanolamines, while concomitantly enabling the attainment of lith quality.
An object of the present invention is to provide a developer composition which does not require the presence of hydroquinone-type developer components or alkanolamines, and as a consequence, poses less of a threat to health and environment and can be more easily handled and disposed.
It is also an object of the present invention to provide a stable developer composition which is adaptable for processing standard rapid access films.
It is another object of the present invention to provide a new method for obtaining a high contrast image by using a non-hydroquinone containing developer and a silver halide photographic material containing a hydrazine compound as a nucleator.
These and other objects of the present invention can be obtained by a non-hydroquinone developer composition consisting essentially of the following:
(a) a developer selected from the group consisting of ascorbic acid and sugar-type derivatives thereof, or alkali metal salts and mixtures thereof, in an amount of 0.1 to 0.4 mol/liter (mol/l);
(b) an effective amount of an auxiliary developer comprising a 3-pyrazolidone compound, an aminophenol compound or a mixture thereof;
(c) an alkali metal sulfite in an amount of less than or equal to 0.32 mol/l;
(d) an alkali metal carbonate in an amount of 0.1 to 0.4 mol/l;
(e) an alkali metal hydroxide in an amount of from 0.08 to 2.0 mols/l;
(f) with the developer composition having a pH of 11.8 or higher at 25xc2x0 C.; and
(g) said developer composition does not contain an alkanolamine or contains an alkanolamine in an amount of less than 5 g/l.
In a preferred embodiment of the present invention, the developer composition additionally contains one or more of the following additional components:
(h) a restrainer to retard the development of non-exposed silver halide present in an amount of from 0.008 to 0.5 mol/l;
(i) an organic antifoggant agent in an amount of 0.02 to 2 g/l; and
(j) a sequestering or chelating agent in an amount of 0.5 to 3 g/l
In accordance with a more preferred embodiment of the present invention, at the same time, the restrainer is selected to be an alkali metal bromide; the organic anti-fogging agent is selected to be a combination of 0.01 to 0.1 g/l benzotriazole and 0.01 to 0.1 g/l phenyl mercaptotetrazole (PMT); and the sequestering or chelating agent is selected to be Na2EDTA.
The developer composition of the present invention does not contain an alkanolamine or contains an alkanolamine in an amount of less than 5 g/l. Most preferably, the developer composition does not contain an alkanolamine. Many alkanolamines possess the undesirable characteristics of toxicity, excessive volatility and unpleasant odor. Many alkanolamines can form azeotropes with water that can complicate accurate replenishment of developer solutions, and such compounds are also quite costly. Furthermore, alkanolamines tend to accelerate the process of chemical development at the expense of physical development. This phenomenon tends to produce an image which is more grainy than an image obtained without an alkanolamine, and is contrary to the goal of obtaining a very high contrast lith image.
The use of the developer composition of the present invention has been found to unexpectedly provide for the attainment of lith quality in an assured manner and therefore high dot quality without the need for the presence of hydroquinone or an alkanolamine.
Another embodiment of the present invention comprises developing an image-wise exposed silver halide photographic material containing a hydrazine compound as a nucleator with a developer comprising a developing agent selected from the group consisting of ascorbic acid and sugar-type derivatives thereof, or alkali salts and mixtures thereof, and substantially free from dihydroxybenzene with the term xe2x80x9csubstantially free from dihydroxybenzenexe2x80x9d meaning the amount of the dihydroxybenzene is less than 5xc3x9710xe2x88x924 mol/l and preferably is zero. The other developer composition components described above can also be employed in combination in this method embodiment of the present invention.